Art of cracking hydrocarbons.



1. w. COAST, 1n, ART OF CRACKING HYDROCARBONS.

APPLICATION FILED MAY 22, 19]?- 1,252,999. Patented Jan. 8,1918.

M (my-w; a V 452% UNITED STATES PATENT OFFICE.

JOHN w. COAST, in, or TULSA, oxLAnonA, Assxenon. TO THE rn'oenss COMPANY, OF TULSA, OKLAHOMA, A CORPORATION or MARYLAND.

ART OF CRACKING HYDROCABBONS.

. Specification of Letters Patent.

Patented Jan. 8, 1918.

Application filed May 22, 1917. Serial No. 170,148.

'1 '0 all hom, it mag concern:

Be it known that I. Jonx I". CoAs'r. Jr.. a citizen of the United States of America, a resident of Tulsa. in the county of Tulsa, State. of ()klahoma, have invented certain new and useful Improvements in the Art of Cracking Hydrocarbons, of which the following is a full. clear, and exact description, reference being bad to the accompanying drawings. forming a part of this specification.

My invention relates to improvements in the art of cracking hydrocarbons. and more particularly to a method of protecting overheated portions of cracking stills.

\Vheu high boiling point petroleum hydrocarbons are cracked in the ordinary cylindrical still, heavy coke forming fractions settle on the still bottom. The resultant coke or carbon is a good heat insulator; it prevents the free transmission of heat from the still bottom to the liquid. and it usually accumulates in a pile at some point directly above the fire. When a sufiicient quantity of this coke has accumulated. a portion of the bottom of the still soon becomes red hot, and some immediate steps must then be taken to avoid a rupture at the'overheated portion of the still. In actual practice, the still is usually permitted to cool and the coke or carbon is then removed. Obviously, this procedure results in a loss of fuel due to the cooling and reheating of the still. the operating expenses are otherwise increased. and the average yield per hour is decreased.

The ob ect of my lIlYEfllllOIl is to eliminate the danger by protecting the overheated portions of the still. thereby increasing the life of the still and permitting it to be operated continuously for a considerable period of time without removing the coke or carbon.

Figure I is a diagrammatieal view of a cracking apparatus. showing a shield adapted for use in carrying out my method.

Fig. II is a horizontal section. showing the heating chamber and the shield mounted therein.

Fig. III is an enlarged horizontal section, showing the interior of the shield.

Fi IV is a section on the line IV-IV, Fig. III.

To illustrate the invention, I have shown a large cylindricalcracking still 1 arranged above a heating chamber, the latter being provided with a grate 2 on which a bed of fire is maintained. The vapor passing from the still flows through an inclined vapor pipe 3, then through an air cooled reflux con-denser 4 to a vapor pipe 5 leading to a main condenser 6, from which the product is recovered. The condenser 6 is preferably a coil arranged in a water tank 7.

The apparatus I have shown is particularly adapted for use in cracking high boiling point products of distillation. such. for example, as distillates or residues resulting from the distillation of crude petroleum. The substances to be treated are iutrmlnced into the still in any suitable manner. and the desired pressure may be obtained by regulating a valve 8. preferably located in the vapor pipe 5. The pressure in the still and reflux condenser 4 is preferably greater than 50 pounds per square inch, and the tempera ture of the contents of the still preferably ranges from about 600 F. to 800 F. The low boiling point fractions passing from the liquid flow through the vapor pipe 3 and reflux condenser 4 to'the pipe 5, leading to .such fractions being returned to the still through the inclined vapor pipe. This reflux condensate includes a large percentage of heavy, coke forming fractions, commingled with lighter fractions which may be redistilled to form part of the low boiling point roduct.

A sliield A, located in a. pocket in the front wall of the heating chamber, is slidably mounted on a horizontal guide consisting of a pair of, pipes9 and 10 connected by a shorter pipe 11 at the front of the still. The pipes 9 and 10, located between the bottom of the still and the fire, are arranged longitudinally of the still. An overflow pipe 9' leads from the condenser to the pipe 9, the water passing from the condenser being circulated throughthe pipes 9 and 10. The shield A is a hollow fire-proof structure, made of metal and provided with baf- I a discharge pipe 14. The pipes 13 and 14 extend through the front wall of the hetiting chamber and serve as handles for manipulating the shield from the exterior of the apparatus. Sleeves 15, forming part of the shield, are loosely fitted to the pipes 9 and 10.

When the still is in service, coke forming fractions will settle on the bottom of the still, and at some point a relatively large body of the coke or carbon will accumulate, as indicated by the dotted lines X in Fig. I. A portion of the still bottom will then be overheated and become red at a point below the coke or carbon. At this time, the operator interposes the shield between the red portion of the still and the heating medium, thereby intercepting the heat so as to protect the coke-covered portion of the still from the heating medium. By protecting the still in this manner, the danger usually due to overheating can be quickly overcome, without cooling the entire still and without removing the coke or carbon from the still. The temperature of the contents of the still is not materially changed, and the continued cracking operation is not materially aflected by the relatively small fireproof shield under the large still.

. x The apparatus herein shown 1s claimed in an application for patent filed by me May 22, 1917, Serial Number 170,147.

I claim:

1. In the art of cracking hydrocarbons, the method of maintaining cracking stills in operation which comprises interposing a shield between an overheated portion of a still and the heating medium.

2. In theart of treating hydrocarbons the method which comprises heating a still to transmit heat to the contents thereof, and thereafter interposin a shield between an overheated portion 0 the still and the heating medium.

3. In the art of cracking hydrocarbons, the method which comprises heating the bottom of a large cylindrical cracking still, and interposing a relatively small shield between the heating medium and an overheated portion of the bottom of the still.

4. In the art of cracking hydrocarbons, the method which com rises heating the bottom of a cracking sti l, permitting coke to accumulate on said bottom, permitting a portion of said bottom to be overheated and become red at a point below said coke, and then interposing a shield between the red portion of the still and the heating medium.

5. In the art of cracking hydrocarbons, the method of maintaining cracking stills in operation which comprises interposing a shield between an overheated portion of a still and the heatin medium, and circulating a cooling fluid t rough said shield.

In testimony that I claim the foregoing I hereunto afiix my signature.

JOHN W. COAST, JR. 

